21212121222 has 24 divisors (see below), whose sum is σ = 45982348776. Its totient is φ = 7067206656.

The previous prime is 21212121209. The next prime is 21212121283. The reversal of 21212121222 is 22212121212.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21212121195 and 21212121204.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 254203 + ... + 327174.

It is an arithmetic number, because the mean of its divisors is an integer number (1915931199).

Almost surely, 2^21212121222 is an apocalyptic number.

21212121222 is an abundant number, since it is smaller than the sum of its proper divisors (24770227554).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21212121222 is a wasteful number, since it uses less digits than its factorization.

21212121222 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 583412 (or 583409 counting only the distinct ones).

The product of its digits is 128, while the sum is 18.

Adding to 21212121222 its reverse (22212121212), we get a palindrome (43424242434).

It can be divided in two parts, 212121212 and 22, that multiplied together give a palindrome (4666666664).

The spelling of 21212121222 in words is "twenty-one billion, two hundred twelve million, one hundred twenty-one thousand, two hundred twenty-two".